Field of the Invention
The present invention is related to the field of foundations for the support of tall, heavy and/or large towers and, more particularly, to a retrofit structure addition and method for reinforcing existing concrete gravity spread foundations currently used to support wind turbines and similar structures, especially those foundations which have failed or are failing due to long term dynamic fatigue.
Description of the Related Art
Concrete gravity spread foundations are often used to support turbines in the 1.5 megawatt (MW) range of which there are several thousand in the U.S. Conventional gravity spread foundation construction relies on reinforced concrete theory and designs which is inappropriate for very dynamic structures like a wind turbine. As a result, these gravity spread foundations are susceptible to long term fatigue failures which can result in collapse of the foundation. Such collapses have been known to occur after as few as 8 to 13 years, well before the expiration of turbine life which is on the order of 20-25 years or more. Therefore, there is a need for a structure and method by which gravity spread foundations may be reinforced to extend their fatigue life well beyond the turbine life.